Battery changeover switch.

[Canuck]

Just re-engined my Warrior with a 4 stroke Yamaha, rewired and fitted twin battery setup. I fitted a change-over switch and every thing checks out fine and all voltages and charging are ok.

Now although I'm ok with electrics I'm no expert, I used the information from Dave S' site Fishing boats and equipement. In the writeup it say's in RED stop engine before switching between batteries and I accept that information, but I have a question for more knowledgeable persons.
I would have thought that I should select position 1 (starting battery) to start and then switch to ALL to charge both batteries then after turning off the engine select 2 (leisure battery) to run other equipement.

Should I start on all?

Will this effect the leisure battery?

Can I start on 1 then switch to both?

What will happen (damage/short?) if I switch while the engine is running (charging).

Hope this makes sense,

Rich.

[Sunny]

Rich, is it the same as this type of switch (below)....I've been using one for several years now. Your battery configuration on a 12v system can only be In Parallel - so it matters not which position the switch is in; as power to start the engine can be drawn from both batteries. If one is low, then the engine will be started by the current from the good battery. All the switch should do is isolate which battery, or batteries, are supplying your toys.

Apparently though - you should not connect BOTH batteries to run In Parallel if one is dead.... that can cause the good battery to rapidly discharge into the dead battery, causing overheat and the potential to explode !!!!

If you wire your batteries incorrectly - In Series - then you create a 24v system...and more problems



Although most trips I have mine set on BOTH batteries I have never really thought about it and I have probably switched between batteries with and without the engine running !!!!

The warning label on the switch - now lost - used to say "don't switch to OFF position whilst engine running"... or similar words. No warnings about switching between batteries whilst the engine was running. I would have thought they would have included that in big letters ?

The only time I bother to isolate one battery is when doing an all-night session, when the lights and radio are left on. But I have LED deck lights, so the power used is minimal. Remember that if your two (or more) battery configuration is In Parallel then all batteries contribute to starting the engine, regardless of their respective states

One thing to observe is that the type of switch shown is a 360 degree spin. Contact allowing power into the 'toys system' seems to be continuous once you leave the OFF position; just varying which batteries supply the system.

I'll watch the results of this...as I've probably been making mistakes ;D

[monkeynuts]

hi rich
years ago you had to be very carfull as the alternaters were bit touchie and could be damaged very easy,but on modern alternaters it wont effect it by changing over to both after starting, thay are so robust now.just never turn the batterys off while the engine is running
cheers john

[Canuck]

Thanks for the replies guy's.

Nick, my switch is similar to the one on your boat, all the voltages are 12v so I should be OK. We'll have to meet up soon.

John, as you say is the way I thought it would be. Its always better to ask if like me your unsure . cheers.

Rich.

[BrianR]

That's the same switch as I had on my previous boat.
It's a "Make Before Break" switch, so you can switch between Battery 1, Both and Battery 2, provided you don't switch via the OFF position.

The way I used mine was:
Switch to Battery 1 to start.
Then switch to Both to charge both batteries.
When I stopped the engine, switch to Battery 2 ("to run the toys").
That way Battery 1 didn't get drained while I was fishing.
Then switch to Battery 1 to start and repeat the above.

The next time out, I'd use battery 2 for starting and Battery 1 while fishing.

Had the boat 10 years and never had a battery problem.

I don't understand Sunny's sentence "All the switch should do is isolate which battery, or batteries, are supplying your toys".

On my new boat I've fitted a Voltage Sensitive Relay.
Battery 1 is for the engine, Battery 2 charged via the VSR runs electronics and lights.

[Sunny]

Brian, I like your suggestion on alternating which battery I use to start and which to use for the 'toys'... I'll be following that from now on.

The quote... I was referring to which battery I use to supply the 'toys'; sorry my poor syntax

I must confess to putting the switch to BOTH to start the session/engine. No harm in this providing you isolate to '1' or '2' if you are spending long periods without the engine on (i.e. overnight sessions)

[BrianR]

Sunny
Reading it again it makes sense now.

[Canuck]

Brian,

The way you used yours is as I thought and as I intend to use mine, I was just thrown by the statement not to changeover with the engine running. My switch is OFF - 1 - BOTH - 2 so I cannot cross over OFF while switching.

Cheers for the input gents

Rich

[BrianR]

Rich

Sorry for the late reply.
If your switch isn't the same as in Sunny's photo, check that it is "Make before Break".

[Canuck]

Had my first runout with the new (secondhand) engine and battery set up. Worked fine (ish) started on 1 turned to both - ok - turned to 2 cough and splutter turned back to both - fine, so will run on both and use 2 after engine switched off for vhf, gps, etc.

Cheers

Rich

[wayner]

I have the same switch as the one in Sunny's pic & all i do is alternate between 1 & 2, ie i run out to a mark on one & back on the other. Both are leisure batteries with enough cold crank for the engine iv got. Not sure you should be experiencing a problem on battery 2 if both your batteries are the same?

[Canuck]

No1 battery is for starting (car battery) and no 2 is a leisure battery for toys etc. I should be alright now.

Rich

[olly]

i have the same switch on my boat if you need i can take some pics of how its wired to the bats

olly

[Salar]

It is really important that you do not leave the switch set to Both, because the batteries will try and balance each other and the good one will be drained by the bad one. Much better to switch to 1 or 2, you can switch when the engine is running as long as you go via the Both setting. I like to start on 1, leave it on 1 to put the charge back up, switch to 2, use 2 to start after fishing, leave on 2 to replace the charge, then switch back to 1. Then I am reasonably confident both batteries are fully charged when I leave the boat. There are more costly and more sophisticated switches that manage your batteries better, but the above method will work as long as you remember to do the switching.